[Zope] Assigning roles in context from groups

[John K. Hohm]

I am using LDAPUserFolder with Zope 2.5.1 to authenticate users.  I have users 
in groups (which show up as roles in Zope) such that the group names are part 
of some folder names, and I want to put the users in roles in the context of a 
folder based on whether they are in a group that matches the folder name and a 
certain role name.  This should allow me to assign permissions to those roles 
in a containing folder and have them apply only to the folders that a user is 
in a group for.

For example, if I put user 'jhohm' in group 'foo_dogs', then 'jhohm' 
automatically has the 'foo_dogs' role, but I also want 'jhohm' to have 
the 'dogs' role in the context of the '/auto/foo' folder; likewise 
for 'bar_dogs' giving 'dogs' in '/auto/bar', etc.  Then I can just assign 
permissions to 'dogs' in '/auto'.

I figured that one way would be to create a product inherited from OFS.Folder 
that defined an __ac_local_roles__ method, but I'm not having much luck with 
that (it seems to do nothing).  Am I even on the right track?